As airlines charge extra for baggage while adding more fee-based amenities such as premium seating and Wi-Fi, it's getting more difficult for travelers to compare the cost of a flight on different carriers.
A push for making comparison shopping easier could require airlines to share data on fares and fees with online travel agencies such as Expedia, Orbitz and Travelocity.
But airlines are resisting, saying they have the right to decide which companies they partner with for sales. While online travel agencies can help airlines push more tickets, the carriers also see them as middlemen that profit from the product sold by airlines — and drive fares down by intensifying competition.
"What's happening is they're blocking competition by blocking comparison," said Kurt Ebenhoch, executive director of Air Travel Fairness, an advocacy group representing travel search companies.
While many travelers want to find the lowest fare, carriers such as Delta Air Lines don't want to be compared with other carriers based solely on price. That, they fear, would result in a race to the bottom in fares.
Instead, Delta and other major carriers want to attract customers willing to pay more for more creature comforts, like extra legroom, Sky Clubs, in-flight Wi-Fi, power outlets and food or beverage options.
The U.S. Department of Transportation in 2016 under the Obama administration started a process to collect public comments on the issue and whether consumers are harmed when airlines restrict where their flights and prices are listed. The process attracted more than 58,400 comments, but was suspended by the Trump administration in 2017.
Ebenhoch hopes for movement with legislation introduced by Sen. Susan Collins, R-Maine, to lift the suspension. But he acknowledged that airlines "are exerting a great deal of pressure" to kill the measure.